Fire damper



Sept. 16, 1969 R. A. VASSAUX 3,467,163

FIRE DAMPER Filed July 19, 1966 4 Sheets-Sheet l INVENTOR. RICARDO A. VASSAUX BY MAHONEY. MILLER 8. RAMBO ATTORNEYS Sam. 16, 1969 R. A. VASSAUX FIRE DAMPER 4 Sheets-Sheet 2 Filed July 19, 1966 INVENTOR. 5 RICARDO A. VASSAUX BY MAHONE Y. MILLER & RAMBO ATTORNEYS Se t. 16, 1969 R. A. VASSAUX FIRE DAMPER 4 Sheets-Sheet 5 Filed July 19, 1966 T/////,/////l/Y// INVENTORV RICARDO A. VASSAUX BY MAHONEY. MILLER 8IRAMBC BY ATTORNEYS Sept. 16, 1969 R. A. VASSAUX FIRE DAMPER 4 Sheets-Sheet 4.

Filed July 19, 1966 EFL-.1.

INVENTOR.

RICARDO A. VASSAUX BY MAHONEY.MILLER & RAMBO Y Y B 44-19% ATTORNE Y5 United States Patent FIRE DAMPER Ricardo A. Vassaux, Columbus, Ohio, assignor to United Sheet Metal Co., Inc., Columbus, Ohio, a corporation of Ohio Filed July 19, 1966, Ser. No. 566,361 Int. Cl. E05f 15/20,- E04f /08; E06b 7/08 US. Cl. 160-l 3 Claims ABSTRACT OF THE DISCLOSURE A folding metal fire wall including a frame with guide tracks in which are mounted a plurality of interhinged metal slats or strips foldable into a compact zig-zag mass adjacent one end of the frame and extendible by unfolding of the hinged slats to fully close the frame opening. The strips are hinged by slidingly interconnecting roll portions along their elongate edges. The cross-section shape of the hinge roll edges of the strips include a major terminating portion constructed on a mathematical spiral joined to the central body of the strips by a portion constructed on a circular basis. A special fusible link retaining assembly holds the folded strips in compact position at one end of the frame until release is dictated by high temperature condition. The cooperating portions of the fusible link assembly provide a secure and operable release arrangement with minimum heat transfer between metal components.

Background of the invention This invention relates, in general, to a folding shutter for a fire-damper. It has to do with that general type of folding shutter which is usually made of elongated metal slats that have adjacent edges hinged together by interlocking bends or curls so that they can pivot relatively and fold on themselves into zigzag or accordian-like fold at one edge of an opening to be controlled 'or can be unfolded to extend across the opening and thereby provide a metal fire barrier or curtain. The present shutter is especially suitable for mounting in a fluidconducting pipe or duct such as is commonly used in heating and air conditioning and to function as a firedamper but is not necessarily limited to that usage.

More particularly, this invention relates to a folding shutter of specific construction having a novel, interlocking hinge structure by which the several slats of the folding shutter are retained in operable association with each other. The interlocking hinge structure is of an improved form which facilitates the relative swinging or pivotal movement of adjacently disposed and interconnected slats while retaining such slats in association with each other.

It has been the practice in manufacturing folding shutters of the type described to roll the longitudinally extending marginal edge portions of adjacent slats into cooperatively shaped bends or rolls which, when interconnected, form a hinge structure. Each rolled edge is formed with a longitudinally extending open space between the terminal edge and a surface of the slat through which an adjacent, interconnected slat projects. Such a hinge structure must be capable of relative swinging movement through an angle of approximately 160 to 180 in order that adjacent interconnected slats may be folded into overlapping relationship. Accordingly, it is important that the rolled edges be formed in such a manner that the pairs of interfitting loops forming a hinge structure are capable of the required angular movement and will not bind or otherwise restrict the swinging movement but which will remain interlocked throughout the movement range and not disengage at any point of relative position. Formation of sharp ir- 3,467,163 Patented Sept. 16, 1969 ice regularities in the surfaces of the loop tend to inhibit the relative rotational movement of the hinge structure. Restriction to movement is undesirable in folding shutter installations and may not be tolerated in fire-damper installations.

Summary of the invention It is, therefore, a primary object of this invention to provide a folding shutter which comprises a plurality of novel interlockng hinged slats with the slats being formed with an improved hinge structure which eliminates binding or interference during operation.

It is a further object of this invention to provide an improved hinge structure for a folding shutter in which interlocking longitudinally extending marginal edge portions of adjacent slats are formed in rolls having a transverse cross section in which the terminal portions of the rolled edge are shaped in accordance with a mathematically definable spiral.

It is another important object of this invention to provide an improved hinge structure for a folding shutter in which each of the slats is provided with a hinge roll along a longitudinal marginal edge portion and in which the rolled hinge edge includes a terminal end portion in the form of a logarithmic spiral.

It is another important object of this invention to provide an improved hinge structure for a folding shutter of the slat type in which the hinge roll edge includes a terminal end portion in the form of a logarithmic spiral connected to the main body of the slat by an intermediate circularly shaped arc portion.

It is a still further object of this invention to provide a folding shutter type fire-damper of novel construction utilizing slats having the marginal edge portions formed with an improved hinge structure including a terminal end portion which is of logarithmic shape.

A further object resides in the provision of a novel assembly of brackets and a fiat fusible link for releasably retaining the folding wall as in the foregoing objects in folded condition, the end loops of the flat fusible link cooperating with embracing notches or recesses in bracket hooks to result in a disposition of the link so that only narrow edge portions of the fiat link contact the metal of the folding wall and of the bracket to minimize conductive transfer of heat away from the link.

These and other objects and advantages of this invention will be readily apparent from the following detailed description of an embodiment thereof and the accompanying drawings.

Brief description of the drawings In the drawings:

FIGURE 1 is a perspective view of a fire-damper structure in which a folding shutter embodying this invention is installed.

FIGURE 2 is a vertical sectional view of the firedamper taken along lines 2-2 of FIGURE 1 and drawn on an enlarged scale to illustrate the structure of the folding shutter in greater detail.

FIGURE 3 is a horizontal sectional view taken along lines 33 of FIGURE 2.

FIGURE 4 is a horizontal sectional view taken along lines 4--4 of FIGURE 2.

FIGURE 5 is an enlarged perspective view of a fusible link and supporting structure therefor which maintains the folding shutter of the fire-damper in a folded configuration.

FIGURE 6 is an enlarged transverse view of a hinge structure which is formed in its entirety in accordance with a predetermined logarithmic spiral.

FIGURE 7 is an enlarged transverse view of the cooperating hinge structure between two adjacent slats which is formed as a composite configuration with the terminal end portion of each hinge roll following a logarithmic spiral and an intermediate portion connecting the terminal portion with the main body of the slat following a circular arc configuration.

FIGURES 8, 9 and diagrammatically illustrate the operation of a hinge structure formed as in FIGURE 7 from a position with the slats in folded relationship in FIGURE 8 to an extended relationship in FIGURE 10.

Having reference specifically to FIGURE 1, a folding shutter embodying this invention is shown in a firedamper installation. Such a fire-damper structure may include an elongated sleeve 11 which may be interconnected with a fluid conduit (not shown) through which gaseous type fluids may be transmitted. The sleeve 11 is of a rectangularly-shapedcross-sectional configuration and may be disposed as shown for incorporation of the firedamper structure to be of a type which is generally in a horizontally disposed fluid conduit. In this specific arrangement, the sleeve 11 includes an upper or top wall 12, a lower or bottom wall 13, and a pair of upstanding, spaced apart side walls 14 which interconnect with the top and bottom walls. The fire-damper structure also comprises a folding shutter indicated generally at which is installed interiorly of the sleeve 11 by means of a suitable supporting frame and is adapted to be either folded into a generally nonobstructing configuration, as shown in FIGURE 1, permitting fluid flow through the sleeve 11 or alternatively, unfolded to an extended configuration extending substantially across the interior of the sleeve in blocking or obstructing relationship to the flow of fluids therethrough. An unfolded shutter configuration is shown in broken lines in FIGURE 2. The illustrated fire-damper structure is of the gravity-operated type and the folding shutter 15 is adapted to be normally supported in folded relationship adjacent the top wall 12 and will extend in response to gravity forces toward the bottom wall 13 when released in response to an increase in temperature of fluids flowing through the sleeve. It is to be understood, however, that a fire-damper structure such as this may be installed in a vertically disposed fluid conduit with incorporation of suitable means for urging the folding shutter into fluid-flow obstructing relationship to the sleeve.

The folding shutter 15 is formed from a plurality of elongated strips or slats 16 which are formed with cooperative interlocking hinge structures extending along each longitudinal edge thereof. The specific configuration of the slats 16 is best seen in FIGURE 2 in which the folding shutter is shown in transverse section. Since a folding shutter which is designed for utilization in a firedamper must be capable of withstanding relatively high temperatures, the slats 16 in the present are formed from a suitable material such as steel. Each of the slats 16 is of the same general cross-section configuration. The extended end pieces of the rolled edges which provide guide lugs extend from the small hinge roll on some slats and on adjacent slats they extend from the large hinge roll. In the installation illustrated in FIGURE 2, the relative relationship of adjacent slats is transposed and all of the slats forming the folding shutter will operate in the same direction and thereby provide a relatively compact unit when folded. The compactly folded shutter will present a minimal obstruction to fluid flow through a conduit connected with the sleeve and which is of the same size. Obstruction to fiuid flow may be further minimized in an installation of the type where the area and configuration of the fluid conduit is substantially equal to the open area of the sleeve at the shutter and the shutter will be effectively out of the fluid stream. The slats are readily formed from a flat sheet of material and each includes a central, main body portion 17 with respective large hinge roll 18 and small hinge roll 19 formed along the opposite longitudinal edges of the main body portion. The large and small hinge rolls 18 and 19 are of a complementary configuration and when interfit'ted as illustrated will form an interlocking hinge structure which will be explained in further detail hereinafter. A folding shutter 15 is as sembled from a suitable number of the individual slats 16 by longitudinally sliding adjacent slats into telescoped relationship with the opposed interfitting large and small hinge rolls 18 and 19 in interlocking engagement.

The uppermost slat 16 of the folding shutter is hingedly connected to the supporting frame to permit relative swinging movement. Forming this hinged connection is an elongated rod of circular cross section which extends transversely between vertical side wall members of the supporting frame in close proximity to the top wall 12. This hinge rod 20 is supported at each end in fixed relationship to the frame. The hinge rod 20 also extends longitudinally of the large hinge roll 18 of the uppermost slat 16 and the relative configuration of the roll and rod are such as to permit rotation of the slat on the hinge rod. If desired, the hinge roll 18 encircling the hinge rod 20 may be deformed from the configuration of the remaining hinge rolls to more accurately follow the circular configuration of the hinge rod for optimum operation.

In accordance with this invention, the large and small hinge rolls 18 and 19 are formed with a transverse crosssectional configuration as is best shown in FIGURE 7. The complementary relationship of the large and small hinge rolls is clearly illustrated in this figure as the hinge structure is shown with the two adjacent slats 16 disposed in fully folded relationship. This fully folded relationship is not attained in the actual structure as the folded rolls occupy a finite space and prevent the main body portions 17 of two adjacent slats from coming into contacting engagement as can be seen by reference to FIGURE 2. In forming the large and small hinge rolls 18 and 19, the respective longitudinal marginal edge portions of the main body portion 17 are turned inwardly forming rolls of hook-shape which are open at one side to permit relative rotational movement of the interlocking hinge loop. Hinge rolls of folding shutter structures fabricated in accordance with prior art have the hinge rolls formed with a cross-sectional shape of empirically determined configuration which will permit the desired swinging movement. The resultant hinge rolls of empirical design formed in accordance with the prior art usually comprise several distinct shapes with sharp irregularities appearing at the juncture of adjacent shapes. These irregularities appearing between adjacent sections of the prior art rolls often result in jamming or binding during relative rotation of two interconnected slats and thereby adversely affect the operation of the shutter.

It has been found that forming the longitudinally extending, marginal edge portion of each hinge roll in accordance with a mathematically defined configuration provides an interlocking hinge structure which eliminates interference to the desired relative rotational movement through approximately of relative rotational movement as experienced with prior art hinge structures but which will remain interlocked throughout the range of movement. This desired mathematically defined configuration comprises a spiral which has a radius of curvature increasing at a predetermined rate from the terminal edge of the roll. Forming the hinge rolls in a spiral configuration provides contacting surfaces which are smooth and unbroken without any marked transition point or sharp irregularity which could result in binding or interference. Accordingly, referring to FIGURE 7, the cross-section shape of the terminal end portion of each of the hinge rolls of the present invention are of a spiral configuration, preferably a logarithmic spiral designated by the letter S, and which are connected with the main body portion 17 by an arcuate portion C. The spiral portion S is initiated on an axis normal to the planes of the main body portion 17 and in spaced relationship to the edge thereof providing an open space between the main body portion and the s iral portion through which the elements of an interfitting roll project. A logarithmic spiral is mathematically defined by the polar equation of r=e wherein r is the radial displacement of a point from the center of the spiral at a specific angular position 0 expressed in radians. The quantity A is a constant of proportionality of the specific spiral. The origin or eye of the spiral illustrated in FIGURE 7 is the origin of the x-y coordinates and lies in the plane of the main body portion 17.

Although the entire hinge roll could be of a configuration as determined by the polar equation for a logarithmic spiral, it is preferred that the logarithmic spiral portions S be connected with the main body portion 17 of the slat by an arcuate extension C. This arcuate extension C is of a constant radius having the same radius of curvature as the adjacent portion of the spiral S. This composite configuration of the hinge rolls is desired as it substan tially reduces the relative size of the hinge roll compared to the overall width of the slat 16. FIGURE 6 illustrates a pair of interlocking slats 16 having hinge rolls 18 and 19 which are formed entirely as a logarithmic spiral. The logarithmic spirals illustrated in FIGURES 6 and 7 are each formed with the same constant of proportionality A and drawn to the same scale. As can be best seen by comparison of the hinge structures shown in FIGURES 6 and 7, the hinge rolls 18 and 19 of FIGURE 7 project a relatively shorter distance from the terminal end of the main body portion 17 of each slat. This minimizes the relative proportion of each slat which comprises the hinge rolls. Minimizing the proportion of each slat 16 comprising a hinge roll provides for a more compact shutter when in a folded configuration.

A spiral configuration of the hinge rolls may follow other mathematically defined configurations and, in particular, may be formed as an Archimedes spiral. An Archimedes spiral is mathematically defined by the polar equation of r=A0. Again r is a radius vector and theta is the polar angle expressed in radians with A being the constant of proportionality for the specific spiral.

The hinge rolls have been described in detail heretofore as to the specific configuration for optimum operation and construction of a folding shutter. The actual rotation movement of two such slats is diagrammatically illustrated in FIGURES 8, 9 and 10. In FIGURE 8, a pair of slats 16 are shown in folded relationship substantially horizontally disposed. FIGURE 2 shows that the folded slats will be disposed at an angle of approximately 1520. As the shutter 15 is unfolded to its extended configuration, the pairs of slats 16 will relatively rotate about their interlocking hinge rolls 18 and 19 to a substantially vertical position as shown in broken lines in the lower portion of FIGURE 2 and in FIGURE 10. FIG- URE 9 illustrates an intermediate position of the two hinge rolls 18 and 19 and it can be seen that only small portions of the surfaces of the hinge rolls are in contacting engagement at this time. Continuing the relative rotation of the slats 16 to an extended position, the point of contact will be seen to change as shown in FIGURE and one slat will be depending from the immediately adjacent slat with the main body portions 17 being substantially vertically aligned. This desired rotational movement of the interlocked slats 16 is effected without binding or interference of the hinge rolls 18 and 19. However, the interlocking slats 16 may not be disengaged as the configuration prevents passage of the terminal end portion of one hinge roll through the open space of the interlocking hinge roll. This advantageous interlocking relationship is illustrated in FIGURE 10 where the lowermost slat has been displaced upwardly to the position shown in broken lines with the terminal end portion thereof in the open space of the upper hinge roll. It can be readily seen in FIGURE 10 that there are now three points of interference as indicated at F, G and H to prevent passage of one hinge roll to the open space of an adjacent interlocking hinge roll. When the slats are placed in other relative angular positions, as in the position of FIGURE 9, it will be apparent that there will be multiple points of interference which will prevent inadvertent disengagement of the slats. Once interlocked, the two slats may not be disengaged except by relative longitudinal displacement of the slats.

A folding shutter 15 constructed in accordance with this invention is shown installed in a sleeve 11 for operation in a vertical plane but it is to be understood that this structure may be installed in a fluid conduit for operation of the shutter 15 in a plane other than vertical as previously indicated. The shutter 15 is normally maintained in a folded configuration adjacent the top wall 12 of the fluid conduit. Since it is desired that the folding shutter be maintained in nonobstructing folded configuration as shown in FIGURE 2, means must 'be provided for supporting the shutter in this elevated folded configuration. In the illustrated embodiment, this supporting means comprises a fusible link assembly 25 carried by the conduit by link-supporting means. The specifically illustrated fusible link 25 comprises a pair of rectangularly shaped bars of elongated configuration which are assembled in overlapped relationship by a suitable bonding means as shown in FIGURE 5. This bonding means comprises a fusible alloy metal which becomes relatively soft and plastic at a specific elevated temperature and loses its ability to effect a structural bond between the two elongated elements 26 and 27 of the link. One end of each element 26 and 27 is relatively enlarged and provided with a central aperture 28 and 29 to facilitate engagement with a suitable supporting means.

Forming the supporting means for the fusible link 25 are a pair of L-shaped brackets 30 positioned centrally of the sleeve 11, which can be considered as part of the shutter frame assembly, with each bracket having a relatively short arm which may be attached to the top wall 12 of, the sleeve by suitable means such as welding and a relatively longer arm which depends downwardly from the top wall. The two depending arms of the bracket 30 are spaced apart a distance slightly greater than the width of the slats 16 and are of a length to project a distance below the shutter 15 when the shutter is arranged in a folded configuration. Formed at the lower end of the longer arm of each bracket 30 is a projecting tongue 31 which is adapted to extend through the respective apertures, 28 and 29, of the fusible link 25. As can be best seen from FIGURE 5, the projecting tongue 31 can be formed by punching a circular hole 32 in the marginal end portion of the bracket 30 and punching a transverse slot 33 from the hole to the external edge of the bracket arm with the end of the bracket arm also being arcuately shaped. The projecting tongue 31 will thus form a hook with the terminal end projecting upwardly. The slot 33 and hole 32 are of a dimension to receive the enlarged end portion of the elongated element of the fusible link. Assembly of the fusible link 25 with the supporting brackets 30 is most readily effected by placing the link in a horizontal position and inserting the enlarged ends through the slots 33 into the central hole 32. At this point, the link 25 may be rotated through an arc of to place the elements 26 and 27 in a vertical position and with the surfaces of the apertures 28 and 29 in contacting engagement with the upwardly facing surface of the projecting tongue 31. Positioning of the link 25 in a vertical plane relative to the surface of the slats minimizes the area of contact between the link and the slats and thereby minimizes the heat transfer from the link to slat providing a faster reaction to temperature change since the slats will not be able to function efficiently as a heat sink. Positioning of the link 25 in a vertical plane also results in obtaining the greatest structural strength of a specific fusible link. To assist in maintaining the link 25 in this vertical configuration, a transverse notch or slot 34 is formed in the upper marginal edge portion of the projecting tongue 31 for receiving the enlarged portion of the respective element 26 or 27. The Width of this slot 34 is substantially equal to the thickness of the respective element 26 or 27 forming upstanding side walls which will engage the surfaces of the respective element 26 or 27 and maintain the link in a vertical position.

With the brackets 30 positioned as illustrated in FIG- URE 2 and with the fusible link 25 installed thereon, the shutter is maintained in a substantially nonobstructing relationship to the flow of fluid through the sleeve 11. Should the temperature of the fluid flowing through the sleeve 11 exceed a predetermined value which is the fusing point of the bonding alloy of the link 25, the link elements 26 and 27 will separate to permit the shutter 15 to position itself in an extended position, as shown in broken lines in FIGURE 2 and substantially blocking fluid flow through the sleeve. As the bonding alloy of the fusible link 25 melts, the elements 26 and 27 will separate and swing downwardly to the positions shown in broken lines in FIGURE 2. With the elements 26 and 27 in this position, there will be no obstruction to movement of the slats 16 of the shutter and the shutter will extend by gravity to the position as indicated in broken lines in the lower portion of FIGURE 2. For optimum operation, it is therefore essential that the links 25 be supported in such a manner that the elements 26 and 27 may readily pivot to their broken line position. 'Iheir rotational movement is greatly enhanced through maintenance of the link 25 in a vertical configuration as shown in FIGURE 5. With each of the elements 26 and 27 thus supported by the brackets 30 and maintained in a vertical plane by the slots 34, it can be seen that the elements 26 and 27 will readily pivot to their depending positions in nonobstructing relationship to the folding shutter permitting the relatively free movement of the shutter.

To assure maintenance of the folding shutter 15 in the desired fluid-obstructing relationship when extended across the sleeve 11, suitable guide means is provided to engage the shutter and maintain the extended shutter in a flat plane. Forming this guide means are two vertical members 35 of the rigid, supporting frame which is positioned in the sleeve 11 (see FIGURES 2, 3 and 4). Each of the vertical members 35 is formed with an elongated channel 36 which extends vertically having spaced parallel flanges 37 and 38 projecting inwardly of the respective sleeve side walls 14. Alternate hinge structures of the folding shutter and comprising the large and small rolls, 18 and 19, are formed to extend a distance longitudinally from each end of the main body portion 17 of the respective slats into cooperative engagement with the respective channel 36 as illustrated in FIGURES 3 and 4. These hinge structural extensions 39 are movable longitudinally of the channel 36 with the flanges of the channel being spaced apart a distance to readily permit such sliding movement. One of the flanges 37 forming the channel 36 is of a greater width projecting a greater distance inwardly of the vertical wall 14 in order that it may overlap the main body portion 17 of the slats and thereby form a more fluid-tight seal with the folding shutter when the shutter 15 is in an extended fluid-obstructing relationship to the sleeve 11. Additional sealing between the folding shutter 15 and the respective side walls 14 is obtained by a vertically extending web 40 of each of the members 35. The web 40 is of a width substantially equal to the width of the slat 16 and is integrally formed with the flange 38 and provides a surface which is parallel to the sleeve side walls 14 but is spaced a distance inwardly therefrom into close, proximate relationship to a respective end edge 17a of the main body of the slats 16 (see FIGURE 3). Formed along the opposite edge of the web 40 is an L-shaped section 41 that facilitates attachment of the vertical member 35 to the sleeve side wall 14. When-the folding shutter 15 is extended into fluid-obstructing relationship to the sleeve, both of adjacent ones of the interconnected slats will not be disposed in a flat plane in sealing engagement with the flange 37 and may be angularly disposed relative to each other with the consequent result that the hinge structures not restrained in the channels 36 may project outwardly of the channels 36 beyond the flanges 38. However, fluids will not readily flow around the ends of the slats 16 since the web 40 will effectively seal the ends.

Further sealing of the shutter in relationship to the sleeve 11 is effected by an additional pair of channels 42 and 43 (see FIGURE 2) which are secured to the respective top and bottom walls 12 and 13 of the sleeve and to the vertical members 35 of the rigid supporting frame. Each of the channels 42 and 43 includes a pair of flanges which project a distance inwardly of the top and bottom walls 12 and 13 and are spaced apart a distance to receive the slats 16 therebetween. One vertical flange of each of the channels 42 and 43 is aligned with the flange 37 of the vertical members 35 and will also form a fluid seal with shutter in the same manner as the flange 37.

The folding shutter 15 is preferably formed with a number of slats 16 having a cumulative width greater than spacing between the top and bottom walls 12 and 13 of the sleeve 11. Thus, when the shutter 15 is extended (see FIGURE 2), two or more slats 16 may be positioned in folded relationship in the channel 43. Although a fluid pressure differential may exist as to the opposite sides of the shutter 15 with the higher pressure at the right side in FIGURE 2 which would tend to cause the slats to swing about their hinge structures and fold upon each other, this action will not cause the lowermost slat to disengage from the bottom of the channel 43. The added weight of the excess slats will adequately resist the pressure differential and accommodate the increased length required as a consequence of the refolding action.

It is readily apparent from the foregoing detailed description of an embodiment of this invention that an improved folding shutter construction is provided which overcomes the disadvantages of the prior art structures. The novel hinge structures comprising interlocking loops which are of spiral form with the terminal portion of each loop being shaped in accordance with a mathematically defined spiral permits relative angular displacement of adjacent interconnected slats through an angle of about with interference free movement. Utilizing a logarithmic spiral configuration minimizes the relative size of the hinge structure loops while retaining the structural strength of the material from which the shutter slats are formed.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to 'be embraced therein.

Having thus described this invention, what is claimed is:

1. A folding wall fire damper assembly comprising: a rectangular frame assembly; a plurality of strips of sheet metal with means hinging adjacent ones of said strips at their adjacent longitudinal edges for zig-zag folding action, said strips being disposed with and guided by cooperation with said frame assembly for movement between a folded, damper open condition, and an unfolded, damper closed condition; and temperature responsive means releasably holding said strips in folded condition; said releasable holding means comprising a flat fusible link with two flat pieces of metal with two flat adjacent surfaces fusibly bonded together, separable under a pre-determined ternperatnre condition, the ends of said link constituting flat eyes coextensive with the fiat link body, and link connecting means connecting each link end to said frame, at least a portion of said link connecting means having a hook shaped means combined with means maintaining said hook shaped means in a substantially pre-determined orientation relative to said frame assembly, said predetermined orientation disposing the planar form of the hook shaped means substantially parallel to any one of said strip longitudinal edges, said hooked shaped means engaging, locating and maintaining the associated fiat eye of said fusible link in a predetermined disposition wherein only a narrow edge of said flat fusible link can engage the end strip of the folded strips and the flat planar shape of said link is maintained transverse to the planar shape of the 10 engaged end strip.

2. A folding wall fire damper assembly as defined in claim 1, wherein said portion of said link connecting means is a metal bracket strip connected to said frame and extending adjacent said folding strips, the end of said bracket strip shaped to provide a hook, said hook being disposed through one end eye of sad flat fusible link and having a notch on the inner marginal edge of said hook adapted to locate and engage the fiat sides adjacent the periphery of said eye of said fusible link to thereby maintain the fusible link in said pre-determined disposition.

3. A folding Wall fire damper assembly as defined in claim 2, wherein similar metal bracket strips with hook shaped ends engage each of the end eyes of said fusible link.

References Cited UNITED STATES PATENTS 790,632 5/1905 Hall 1601 1,205,707 11/1916 Cahill 160235 X 1,987,774 1/1935 Hall 16-178 X 2,093,054 9/1937 Negrini 160235 2,586,561 2/1952 Poggi 160235 X 3,242,523 3/1966 Daley 16-171 3,273,632 9/1966 McCabe 1601 15 1,729,825 10/1929 Gaiser 160-235 X 2,903,057 8/1959 Aluarez 160133 PETER M. CAUN, Primary Examiner US. Cl. X.R.

' g;;g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 .467, 163 Dated September 16, 1969 Inventor(s) R.A. Vassaux It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 37, insert "a" before -zigzag-.

Column 5, line 41, change "rotation" to -rotational-.

Column 8, line 63, (Claim 1) change "with" to -within--.

QIGNED Alia SEALED BESZ 'W (SEAL) Attest:

EdmElM'FlmherIr' WILLIAM 1:. 50mm, J Amsting Officer Commissioner of Patent 

